I purchased the Dell PowerEdge T20 several years ago for an Unraid server build that I use to back up my data. One of the unfortunate design flaws of this system is the lack of an intake fan for system and specifically hard drive cooling. I had completed this mod around 2016; however, recently I had noticed that my unraid hard drive temperatures were consistently in the 102-110 Farenheight range when they had previously been much lower. I suspected that the intake fan I had installed several years ago had failed and decided to replace it. I also remembered that when I had originally purchased this unit I recall several people online looking for ways to do this exact mod so I decided to take a picture and post instructions on how to do this.
The fan I am using is the Cooler Master Sleeve Bearing 80mm Slim Fan. Installation is fairly straight forward, after removing the front panel, use either adhesive such as 3M double-sided tape or high strength string to tie the fan in place (see below). Either option works- I had originally used double-sided tape but this time opted to use suture material I had handy. After installation my temperatures returned to 92-95 Farenheight.